Betaine surfactants and preparation methods and uses thereof

ABSTRACT

Betaine surfactants of formula (I) and preparation methods and uses thereof are provided. The surfactant can decrease the interfacial surface tension of crude oil till 10 −3  mN/m, have the capabilities of antiheating (130° C.), antimineralizing and antidiluting, and can be used in the field of tertiary oil recovery.

The present application is the national phase application of PCTApplication No. PCT/CN2011/000389, filed Mar. 11, 2011, the entirety ofwhich is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to surfactants, in particular, to betainesurfactants and the preparation and uses thereof.

BACKGROUND OF THE INVENTION

The main oilfields in China such as Daqing oilfield, Shengli oilfield,and Liaohe oilfield etc. have entered the late stage of secondary oilrecovery having high water cut and extra-high water cut. In order toimprove the ultimate recovery of the existing oilfields, it is desirableto exploit tertiary oil recovery technique. Combined chemical floodingtechnique is a new tertiary oil recovery technique developed in 1980's,which combines alkali, surfactant and polymer and takes advantage of thesynergistic effect between each agent. Such technique not only cansubstantially reduce the interfacial tension of oil-water and increasethe microscopic oil displacement efficiency, but also can increase theviscosity of the displacing fluid so as to have relatively high sweptefficiency, thereby substantially improving the recovery efficiency. Inpractice, due to the use of the strong alkali and the too high dosage,sonic disadvantages are observed, such as the alkali consumption andscaling, damage of formation, decrease of the viscosity of displacingfluid, and the severe oil/water emulsification, which significantlyincreases the difficulty in the treatment of produced liquid and cost,affects the lifting technique in oil production and causes severefacility corrosion. Therefore, alkali, especially strong alkali shouldbe avoided in combined flooding. The systems with weak alkali or withoutalkali have higher viscosity and elasticity than that of strong alkaliASP flooding, which can reduce the amount of polymer and increase thesweep efficiency. Moreover, the formulation on the spot, devices forinjection and processing of such systems are easier than those of ASPsystems, which can reduce the cost. Therefore, it is the developingtrend of the combined flooding to use weak alkali and alkali-freesystems, to which the oilfield developers have paid increasingattention. However, at present, the biggest constraint for developingweak alkali/alkali-free systems is the development of high efficiencysurfactants. Compared with strong alkali ASP flooding, weakalkali/alkali-free combined flooding weakens the effect of alkali, thusmaking it more difficult to reach ultra-low interfacial tension.Presently, the surfactants in research remain at the stage of laboratoryscreening with high cost, which cannot satisfy the need of practicalproduction.

Betaine surfactants are amphoteric surfactants. Due to their chelatingeffect on metal ions, most of the betaine surfactants can be used foroil displacement of high salinity and high temperature reservoirs, andare capable of substantially reducing the chromatographic separationeffect which occurs when nonionic surfactant is combined with anionicsurfactant. The betaine surfactants mainly include carboxyl betaine typeand sulfo-betaine type. The use of sulfo-betaine amphoteric surfactantsin tertiary oil recovery has been reported in US patents. Suchsurfactants solutions prepared by high salinity water with high divalention content are very effective in reducing the oil-water interfacialtension, and have good emulsification and solubilization properties.Darling Petroleum College has successfully developed a new carboxylbetaine BS13 surfactant system. The results of in-lab displacingexperiment show that BS13 oil-displacing system has betteroil-displacing effect than strong alkali ASP system. However, thesynthetic routes of such surfactant BS13 is complicated, with high cost,and the production craft needs to be improved.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a betaine surfactantwhich is tolerant to brine and water with high salinity, and is capableof reaching ultralow interfacial tension in low concentration when usedfor binary combined flooding.

The betaine surfactant is represented by formula (I):

wherein at least one of m and n is a positive integer greater than 0, R₁and R₂ are independently H or alkyl, R₃ and R₄ are independently alkyl,X is selected from the group consisting of

m and n are positive integers of 2-10, and m+n=5-19, R₁ and R₂ areindependently H or C1-C8 alkyl, R₃ and R₄ are independently C1-C4 alkyl.

m+n is an integer of 9-17, R₁ and R₂ are independently H or C1-C4 alkyl,R₃ and R₄ are independently C1-C2 alkyl.

m and n are 7 or 8 respectively, and m+n=15, R₁ and R₂ are independentlyH or C1-C2 alkyl.

The specific structures of the betaine surfactant as described above areselected from the group consisting of:

The process for preparing the betaine surfactants as described abovecomprises the steps of:

(1) Friedel-Crafts alkylation: Friedel-Crafts reaction between olefinicacid or olefinic acid ester and alkylbenzene or benzene catalyzed byprotonic acid takes place to produce aryl alkyl carboxylic acid or arylalkyl carboxylate;

(2) Hydrogenation reduction: the aryl alkyl carboxylic acid or arylalkyl carboxylate is de-esterified to remove the protective groups viacatalytic hydrogenation, so as to produce aryl fatty alcohol;

(3) Amination: aryl fatty tertiary amine is produced from aryl fattyalcohol and secondary amine through Cu—Ni composite catalyst;

(4) Quaternization: aryl fatty tertiary amine is reacted with sodiumchlorohydroxypropyl sulfonate or sodium chloroacetate to produce thetarget product.

The olefinic acid is oleic acid.

The olefinic acid ester is olefinic acid methyl ester.

The alkylbenzene is selected from the group consisting of toluene,xylene and ethylbenzene.

The secondary amine is selected from the group consisting ofdimethylamine and diethylamine.

The reaction condition of quaternization is: aryl fatty tertiary amineis reacted with chlorohydroxypropyl sulfonate or sodium chloroacetate inmethanol solvent at 130° C. and 0.3 MPa, so as to produce the targetproduct.

The reaction condition of amination is: aryl fatty alcohol is reactedwith gaseous secondary amine at 180-250° C. and 0.3 MPa under thecatalysis of Cu—Ni composite catalyst (please see patent CN1316297,CN1110629, and China Surfactant Detergent & Cosmetics, Vol. 25, issue 2,2005), yielding aryl fatty tertiary amine.

The reaction condition of Friedel-Crafts alkylation is: reactalkylbenzene or benzene with olefinic acid or olefinic acid methyl esterin an amount of 5 times of the amount of alkylbenzene or benzene in thepresence of protonic acid catalyst at 115-120° C. and 0.2 MPa, yieldingaryl alkyl carboxylic acid methyl ester.

The protonic acid is selected from the group consisting ofmethanesulfonic acid, phosphoric acid, sulfuric acid and hydrofluoricacid.

The reaction condition of hydrogenation reduction is: aryl alkylcarboxylic acid or aryl alkyl carboxylic acid methyl ester ishydrogenation reduced into aryl a octadecyl alcohol under the catalysisof CuO—ZnO—Cr₂O₃ hydrogenation catalyst at 200-350° C. and 25-30 MPa.

The betaine surfactants of the present invention are prepared by theFriedel-Crafts reaction between olefinic acid or olefinic acid ester andbenzene or alkylbenzene followed by hydrogenation to produce aromaticfatty alcohol. The aromatic fatty alcohol is reacted with tertiary amineto produce aromatic fatty tertiary amine, which is further reacted withsodium chlorohydroxypropyl sulfonate or sodium chloroacetate to producethe betaine surfactants of the present invention. The alkylbenzene isselected from the group consisting of monoalkylbenzene anddialkylbenzene. The C chain of the substituted alkyl is preferablyC1-C8, more preferably C1-C4, and most preferably C1-C2. The substitutedalkyl in secondary amine R₃NR₄ is preferably C1-C4. Since it is betterto use gaseous secondary amine in the reaction, the substituted alkyl insecondary amine R₃NR₄ is more preferably C1-C2. Most preferably, the twoalkyl substituents are simultaneously C1 or C2, that is, the secondaryamine is selected from the group consisting of diethylamine anddimethylamine. The structure of the olefic acid or olefic acid estercomprises C8-C22, more preferably C12-C20, most preferably the length ofthe C chain is 18 (m=7-8, n=7-8, m+n=15, i.e., oleic acid or oleate).Since the hydrogenation condition for aryl alkyl carboxylic acid formedby oleic acid is harsher, oleic acid is preferably esterified prior tothe reaction. The hydrogenation is easier especially when oleic acidmethyl ester is obtained.

The embodiments of the present invention produce octadecylsulfo betainecontaining aryl groups from cheap industrial starting materials such asoleic acid and toluene or m-xylene and the like successively subjectedto esterification, Friedel-Crafts alkylation, hydrogenation reduction,amination and quaternization. The starting materials for this syntheticroute are cheap, and the synthetic route is well-developed and has highyield. In addition, the product comprises aryl groups desired fortertiary oil recovery, which is because it is necessary to incorporatearyl groups into carbon chains to improve the compatibility with crudeoil due to the presence of a large number of aromatic compounds inpetroleum oil.

The synthetic route of the present invention is as follows:

DESCRIPTION OF DRAWINGS

FIG. 1 is the infrared spectrum of the product of step 3 in example 1;

FIG. 2 is the ¹H-NMR spectrum of the product of step 3 in example 1;

FIG. 3 is the infrared spectrum of the product of step 4 in example 1;

FIG. 4 is the ¹H-NMR spectrum of the product of step 4 in example 1;

FIG. 5 is the infrared spectrum of the product of step 5 in example 1;

FIG. 6a is the ¹H-NMR spectrum of the product of step 5 in example 1;

FIG. 6b is the attribution of the signals of the ¹H-NMR spectrum of FIG.6 a;

FIG. 7a is the ¹H-NMR spectrum of the target product in example 2;

FIG. 7b is the attribution of the signals of the ¹H-NMR spectrum of FIG.7 a;

FIG. 8 is the surface tension of binary system, wherein the polymer ishydrophobic polyacrylamide P19000000, 2000 ppm;

FIG. 9 is the surface tension at low concentration of unitary system;

FIG. 10 shows the effect of temperature on interfacial tension;

FIG. 11 shows the effect of salinity on interfacial tension;

FIG. 12 shows the effect of divalent ion on interfacial tension; and

FIG. 13 shows the results of artificial homogenous core displacement fordifferent systems of the surfactants of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Example 1

(1) Esterification: oleic acid is mixed with excess amount of methanol,and concentrated sulfuric acid or p-toluenesulfonic acid is added ascatalyst. The mixture is heated to reflux for 10 h. The mixture iscooled and neutralized to pH 8-9 with sodium methoxide, washed toneutral with water, dried with anhydrous calcium chloride and distilledunder reduced pressure, yielding oleic acid methyl ester;(2) Friedel-Crafts alkylation: m-xylene (3.5 mol) and methanesulfonicacid (0.75 mol) are added into sealed reactor. The mixture is purgedwith nitrogen for 10 min at room temperature, and raised to 120-135° C.at 0.15 MPa. The reaction product of step (1) alkenyl carboxylic acidmethyl ester (1 mol) is added dropwise, the addition time beingcontrolled in 6 h. After the completion of the addition, the reaction iscontinued for 3 h. The reaction mixture is cooled to room temperature,allowed to stand for layering. Iced water having a volume equivalent tothat of the methanesulfonic acid is slowly added. The mixture is rinsed3 times, and lower layer of aqueous solution of methanesulfonic acid isseparated and recovered for storage. The upper liquid is washed withiced water for 3 times, dried, and refined at 100 MPa and 220° C. toyield aryl alkyl carboxylic acid methyl ester. The conversion ratio ofalkenyl carboxylic acid methyl ester is above 95% as measured by Gaschromatography-mass spectrometry with external standard;(3) Hydrogenation reduction: the reaction product of step (2) xylenemethyl oleate is hydrogenation reduced to xylene α octadecanol byhydrogenation catalyst CuO—ZnO—Cr₂O₃ at 200-350° C. and 25-30 MPa. Thedetermination of structure is shown in FIGS. 1 and 2.

Infrared Spectrum:

As shown in FIG. 1, there is a relatively large associative O—Hstretching vibration peak of alcohol at 3332.64 cm⁻¹. The peak at1055.93 cm⁻¹ (stretching absorption of C—O bond) proves the presence ofprimary amine. There are peaks at 3008.96 cm⁻¹ (stretching vibration ofAr—H); 1608.60 cm⁻¹, 1501.96 cm⁻¹ (skeletal vibration of benzene ring);817.48 cm⁻¹ (out-of-plane deformation vibration of Ar—H ofmeta-di-substituted benzene); 2925.49 cm⁻¹, 2853.67 cm⁻¹ (stretchingvibration of saturated C—H of methyl); 1461.45 cm⁻¹, 1375.93 cm⁻¹(bending vibration of C—H of methyl).

¹HNMR:

As shown in FIG. 2, from ¹HNMR data, it is indicated that the molecularstructure is substantially consistent, that is, the product obtained issubstantially consistent with theoretical values.

(4) Amination: the reaction product of step (3) xylene α octadecanol isreacted via Cu/Ni composite catalyst with excess amount of gaseousdimethylamine at 180-250° C. and 0.3 MPa, yielding xylene α octadecyltertiary amine. The spectra confirming the structure are shown in FIGS.3 and 4.

Infrared Spectrum:

As shown in FIG. 3, there are peaks at 3018.15 cm⁻¹ (stretchingvibration of Ar—H); 1607.27 cm⁻¹, 1512.95 cm⁻¹ (skeletal vibration ofbenzene ring); 815.33 cm⁻¹ (out-of-plane deformation vibration of Ar—Hof para-substituted benzene); 2926.35 cm⁻¹, 2854.16 cm⁻¹ (stretchingvibration of saturated C—H of methyl); 1461.95 cm⁻¹, 1376.25 cm⁻¹(bending vibration of C—H of methyl).

¹HNMR:

As shown in FIG. 4, from ¹HNMR data, it is indicated that the molecularstructure is substantially consistent, that is, the product obtained issubstantially consistent with theoretical values.

(5) Quaternization: the reaction product of step (4) xylene α octadecyltertiary amine is reacted with equivalent amount of sodiumchlorohydroxypropyl sulfonate in methanol solvent at 130° C. and 0.3MPa, yielding target betaine surfactant. The spectra confirming thestructure are shown in FIGS. 5 and 6.

Infrared Spectrum:

As shown in FIG. 5, there is a relatively large associative O—Hstretching vibration peak of alcohol at 3421.18 cm⁻¹. There are peaks at3008.96 cm⁻¹ (stretching vibration of Ar—H); 1637.63 cm⁻¹, 1463.2 cm⁻¹(skeletal vibration of benzene ring); 816.48 cm⁻¹ (out-of-planedeformation vibration of Ar—H of meta-substituted benzene); 2925.30cm⁻¹, 2853.57 cm⁻¹ (stretching vibration of saturated C—H of methyl);1199.82 cm⁻¹ (antisymmetric stretching vibration of —SO₃); around1042.35 cm⁻¹ (stretching vibration of C—N of tertiary amine); 629 cm⁻¹(out-of-plane bending vibration of —SO₃).

¹HNMR:

As shown in FIGS. 6a and 6b , from ¹HNMR data, it is indicated that themolecular structure is substantially consistent, that is, the productobtained is substantially consistent with theoretical values.

Example 2 Steps 1-4 are as Described in Example 1

(5) The reaction product of step (4) xylene α octadecyl tertiary amineis reacted with sodium chloroacetate in methanol solvent at 130° C. and0.3 MPa, yielding target betaine surfactant. The spectra confirming thestructure are shown in FIGS. 7a and 7 b.

INDUSTRIAL APPLICABILITY Example (1) Ultralow Interfacial TensionTesting of Binary System

For the target product of example 2, the oil/water interfacial activityin the 6^(th) oil production plant of Daqing oilfield conditions isshown in FIG. 8. For binary system, the interfacial tension reachesultralow level (10⁻³ mN/m or lower magnitude) at a surfactantconcentration in a range of 0.05 wt %-0.3 wt %, indicating the excellentperformance of the sample in kilogram scale of the synthesized newbetaine surfactant.

(2) Ultralow Interfacial Tension Testing of Unitary System

New aryl alkyl betaine surfactants have excellent capability andefficiency of reducing interfacial tension, and in particular, they showgood interfacial activities at rather low concentration. For the unitarysystem of the surfactant of example 1 at a concentration of 50-500 ppm,the oil/water interfacial tension in the 3^(th) oil production plant ofDaqing oilfield conditions is shown in FIG. 9. It can be seen that theinterfacial tension reaches ultralow and the interfacial performance areexcellent within surfactant concentration range of 50-500 ppm.

(3) Effect of Temperature on Interfacial Activity

The crude oil and the recycled produced water of the 4^(th) oilproduction plant of Daqing oilfield are used and the testing temperatureis changed. It is found that for the surfactant of example 1, thefluctuation of interfacial tension is little as the temperature changes,as shown in FIG. 10.

(4) Effect of Salinity and Divalent Ions on Interfacial Tension

One prominent feature of amphoteric surfactants is the high tolerance tobrine and divalent ions. Therefore, the tolerance to divalent ions andthe adaptability for salinity of the betaine surfactants of examples 1and 2 are investigated.

The effect of salinity on interfacial tension is shown in FIG. 11. Itcan be seen from FIG. 11 that the betaine surfactant of example 1 showsa tolerance to salinity of up to 150000 mg/L, and is applicable to theformation water of most of the oilfields.

The effect of the divalent ions on the interfacial tension of thebetaine surfactant of example 2 is investigated by adding calciumchloride into the formation water in Daqing, as shown in FIG. 12. It canbe seen from FIG. 12 that the interfacial tension can still reachultralow when the concentration of divalent ions reaches 1,500 mg/L.

(5) The Oil-Displacing Experiment Comparison of Artificial HomogenousCore Displacement for Different Oil-Displacing Systems

Alkali-free binary system, binary system comprising Na₂CO₃ and Na₃PO₄ assacrificial agents and ASP system comprising NaOH show good oildisplacing efficiency. The oil displacing efficiencies of the oildisplacing approaches as mentioned above are tested on homogeneous core,and the results are shown in FIG. 13, wherein Approach 1 is syntheticsulfo-betaine surfactant 0.2%+polymer 2500 mg/l, 0.35 PV; Approach 2 issynthetic sulfo-betaine surfactant 0.2%+polymer 2500 mg/l+Na₃PO₄ 0.4%,0.35 PV; Approach 3 is synthetic sulfo-betaine surfactant 0.3%+polymer2500 mg/l+NaOH 1%, 0.35 PV. It should be noted that the protective plugin each approach is P 1000 mg/l 0.20 PV.

The increase in recovery efficiency of alkali-free binary system iscomparable to that of the ASP system comprising NaOH, and the recoveryefficiency of binary system combination flooding comprising Na₃PO₄ asthe sacrificial agent is slightly higher than those of the former twoapproaches.

The present invention produces aryl alkyl betaines from cheap startingmaterials in market (oleic acid and alkylbenzene) successively subjectedto esterification, Friedel-Crafts alkylation, hydrogenation reduction,amination and quaternization. The products of the present invention havefive advantages: 1) the reactions are well-developed and the conversionrate is high; 2) the starting materials are cheap and readily available;3) the aryl groups are present in the middle of the carbon chain; 4) theproducts have high activities and are able to reduce the interfacialtension for crude oil of No. 1-6 oil production plants of Daqingoilfield to 10⁻³ mN/m magnitude without the addition of alkali; 5) theproducts have high tolerance to temperature (130° C.), salinity anddilution, and are very promising for application in the field oftertiary oil recovery.

The invention claimed is:
 1. A betaine surfactant of formula (I):

wherein m and n are integers of 2-10, R₁ is H or alkyl, R₂, R₃ and R₄are independently alkyl, and X is selected from the group consisting of


2. The betaine surfactant of claim 1, wherein m+n=5-19.
 3. The betainesurfactant of claim 2, wherein m+n is an integer of 9-17.
 4. The betainesurfactant of claim 3, wherein m and n are positive integers of 7 or 8,and m+n=15.
 5. The betaine surfactant of claim 1, wherein R₁ is H orC1-C8 alkyl, R₂ is C1-C8 alkyl, and R₃ and R₄ are independently C1-C4alkyl.
 6. The betaine surfactant of claim 1, wherein R₁ is H or C1-C4alkyl, R₂ is C1-C4 alkyl, and R₃ and R₄ are independently C1-C2 alkyl.7. The betaine surfactant of claim 1, wherein R₁ is H or C1-C2 alkyl,and R₂ is C1-C2 alkyl.
 8. The betaine surfactant of claim 1, wherein thepara position of —CH(CH₃(CH₂)_(m)(CH₂)_(n)CH₂NR₃R₄CH₂X is H.
 9. Thebetaine surfactant of claim 8, wherein R₁ and R₂ are at meta positionsof —CH(CH₃(CH₂)_(m)(CH₂)_(n)CH₂NR₃R₄CH₂X, and both R₁ and R₂ are methyl.10. The betaine surfactant of claim 8, wherein R₁ is H, and R₂ ismethyl.
 11. The betaine surfactant of claim 8, wherein R₁ is H, and R₂is ethyl.